New evidence of Younger Dryas extraterrestrial impact

(Santa Barbara, Calif.) –– An 18-member international team of researchers that includes James Kennett, professor of earth science at UC Santa Barbara, has discovered melt-glass material in a thin layer of sedimentary rock in Pennsylvania, South Carolina, and Syria. According to the researchers, the material –– which dates back nearly 13,000 years –– was formed at temperatures of 1,700 to 2,200 degrees Celsius (3,100 to 3,600 degrees Fahrenheit), and is the result of a cosmic body impacting Earth.

These new data are the latest to strongly support the controversial Younger Dryas Boundary (YDB) hypothesis, which proposes that a cosmic impact occurred 12,900 years ago at the onset of an unusual cold climatic period called the Younger Dryas. This episode occurred at or close to the time of major extinction of the North American megafauna, including mammoths and giant ground sloths; and the disappearance of the prehistoric and widely distributed Clovis culture. The researchers’ findings appear today in the Proceedings of the National Academy of Sciences.

“These scientists have identified three contemporaneous levels more than 12,000 years ago, on two continents yielding siliceous scoria-like objects (SLO’s),” said H. Richard Lane, program director of National Science Foundation’s Division of Earth Sciences, which funded the research. “SLO’s are indicative of high-energy cosmic airbursts/impacts, bolstering the contention that these events induced the beginning of the Younger Dryas. That time was a major departure in biotic, human and climate history.”

Microscopic Images of Grains of Melted Quartz

These are microscopic images of grains of melted quartz from the YDB cosmic impact layer at Abu Hureyra, Syria, showing evidence of burst bubbles and flow textures that resulted from the melting and boiling of rock at very high temperatures. (Light microscope image at left; SEM image at right.) Credit: UCSB

Morphological and geochemical evidence of the melt-glass confirms that the material is not cosmic, volcanic, or of human-made origin. “The very high temperature melt-glass appears identical to that produced in known cosmic impact events such as Meteor Crater in Arizona, and the Australasian tektite field,” said Kennett.

“The melt material also matches melt-glass produced by the Trinity nuclear airburst of 1945 in Socorro, New Mexico,” he continued. “The extreme temperatures required are equal to those of an atomic bomb blast, high enough to make sand melt and boil.”

The material evidence supporting the YDB cosmic impact hypothesis spans three continents, and covers nearly one-third of the planet, from California to Western Europe, and into the Middle East. The discovery extends the range of evidence into Germany and Syria, the easternmost site yet identified in the northern hemisphere. The researchers have yet to identify a limit to the debris field of the impact.

Photos of Melt Glass Known as Trinitite

These are photos of melt glass known as trinitite formed at the ground surface from the melting of sediments and rocks by the very high temperatures of the Trinity nuclear airburst in New Mexico in 1945. This material is very similar to the glassy melt materials now reported from the cosmic impact YDB layer, consistent with the very high temperature origin of the melt materials in the YDB layer. Credit: UCSB

“Because these three sites in North America and the Middle East are separated by 1,000 to 10,000 kilometers, there were most likely three or more major impact/airburst epicenters for the YDB impact event, likely caused by a swarm of cosmic objects that were fragments of either a meteorite or comet,” said Kennett.

The PNAS paper also presents examples of recent independent research that supports the YDB cosmic impact hypothesis, and supports two independent groups that found melt-glass in the YDB layers in Arizona and Venezuela. “The results strongly refute the assertion of some critics that ‘no one can replicate’ the YDB evidence, or that the materials simply fell from space non-catastrophically,” Kennett noted.

He added that the archaeological site in Syria where the melt-glass material was found –– Abu Hureyra, in the Euphrates Valley –– is one of the few sites of its kind that record the transition from nomadic hunter-gatherers to farmer-hunters who live in permanent villages. “Archeologists and anthropologists consider this area the ‘birthplace of agriculture,’ which occurred close to 12,900 years ago,” Kennett said.

“The presence of a thick charcoal layer in the ancient village in Syria indicates a major fire associated with the melt-glass and impact spherules 12,900 years ago,” he continued. “Evidence suggests that the effects on that settlement and its inhabitants would have been severe.”

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Other scientists contributing to the research include Ted Bunch and James H. Wittke of Northern Arizona University; Robert E. Hermes of Los Alamos National Laboratory; Andrew Moore of the Rochester Institute of Technology; James C. Weaver of Harvard University; Douglas J. Kennett of Pennsylvania State University; Paul S. DeCarli of SRI International; James L. Bischoff of the U.S. Geological Survey; Gordon C. Hillman of the University College London; George A. Howard of Restoration Systems; David R. Kimbel of Kimstar Research; Gunther Kletetschka of Charles University in Prague, and of the Czech Academy of Science; Carl Lipo and Sachiko Sakai of California State University, Long Beach; Zsolt Revay of the Technical University of Munich in Germany; Allen West of GeoScience Consulting; and Richard B. Firestone of Lawrence Berkeley National Laboratory.

Leaving aside the local problems these impacts cause,presumably the impact sent a dust cloud into the atmosphere and led to a world wide cooling. I always thought mammoths became extinct because the Ice Age ended and they could not cope with higher temperatures!
Since this has only just been discovered it could not have been as calamitous for the planet as the evnt 65,000,000 years ago that led to the extinction of the dinosaurs.

Which means that the Younger Dryas was not part of a “natural rythm”, that the natural rythm induced ice age ended 20,000 years ago and not 12,000 years ago. Implications: we are now due for the next ice age.

“He added that the archaeological site in Syria where the melt-glass material was found –– Abu Hureyra, in the Euphrates Valley –– is one of the few sites of its kind that record the transition from nomadic hunter-gatherers to farmer-hunters who live in permanent villages. “Archeologists and anthropologists consider this area the ‘birthplace of agriculture,’ which occurred close to 12,900 years ago,” Kennett said.

“The presence of a thick charcoal layer in the ancient village in Syria indicates a major fire associated with the melt-glass and impact spherules 12,900 years ago,” he continued. “Evidence suggests that the effects on that settlement and its inhabitants would have been severe.”

Interesting – but I’m confused. The article says “Morphological and geochemical evidence of the melt-glass confirms that the material is NOT cosmic, volcanic, or of human-made origin.”. But then they go on to state that the widely distributed material was “likely caused by a swarm of cosmic objects that were fragments of either a meteorite or comet”.

LearDog says:
June 13, 2012 at 4:46 am
Interesting – but I’m confused. The article says “Morphological and geochemical evidence of the melt-glass confirms that the material is NOT cosmic, volcanic, or of human-made origin.”. But then they go on to state that the widely distributed material was “likely caused by a swarm of cosmic objects that were fragments of either a meteorite or comet”.
Aren’t those things “cosmic”?

The objects that hit were cosmic, but the melt-glass is terrestrial. The airbursts (since we haven’t found any craters) essentially melted the ground beneath them and the shock waves carried the molten material outward from “ground zero”…

What’s interesting is that a major cooling from an impact causes a semi-permanent shift to an ice-age-like climate. The impact effects themselves couldn’t have lasted more than a couple decades, yet the climate-change lasted 1000 yrs. This prb’ly happened by similar mechanisms to the “regular” transitions to glacial conditions from interglacials, just faster.

Leaving aside the local problems these impacts cause, presumably the impact sent a dust cloud into the atmosphere and led to a world wide cooling. I always thought mammoths became extinct because the Ice Age ended and they could not cope with higher temperatures!
Since this has only just been discovered it could not have been as calamitous for the planet as the evnt 65,000,000 years ago that led to the extinction of the dinosaurs.

Andrew, I think, as usual, that the evidence is still a little sparse but it remains a serious possibility. The reasoning goes like this :

The mamoths that have been found frozen have been found with food still preserved in their stomachs. For that to happen the animal would have to have been frozen extremely rapidly. Bearing in mind the size of the animal, the russians have calculated a temp of -120°C would have been needed almost instantaneously because the food would have fermented rapidly while the body cooled slowly.
Also, the mamoths would have needed a large supply of food to live where they were frozen. This indicates that the climate was as warm as, or warmer than today. The comet hypothosis for a rapid freeze of this nature seems reasonable but so does a large volcanic eruption if we bear in mind that the YD episode was short lived and very sudden. The previous hypothosis of a glacial block in the US also stands up to a little scrutiny.

Has anyone else noticed an increase in the last few decades of catastrophism for explaining several significant geologic and historic events, a departure from continued application of uniformitarianism? This appears to be what more recent field evidences are suggesting.

I wonder whether the impacts were so severe as to cause ice age conditions – or of the impacts merely lowered the temperature to just beneath whatever the threshold is to cause the shift to an ice age. Note also that the original 12.9k impact theory suggested that one occurred just over the massive ice shelf covering the Hudson bay, that this caused a massive flush of melt water into the Atlantic ocean, affecting the ocean circulation as well as throwing up a dust cloud for a year or more.

What is most interesting to me about this article is that it gives evidence that the impact was in fact multiple impacts. So just how many were involved? So far there is evidence for at least three (North America, Germany, and Syria), but there may possibly have been a dozen or more of various severity.

It has been interesting seeing how this theory has changed as more information became known. Initially they were proposing a supernova as being responsible – however directly or indirectly – for causing the comet impact (1), and back then then [2005] they still believed it was just one impact – possibly directly upon the last major ice sheet over the Hudson Bay. Now they are suggesting multiple air bursts, and I do not recall seeing even one mention of a supernova in the article. On the other hand, there was at least one other article, from 2007, that suggested a more active sun instead of a supernova accounted for some of their suggested evidence of a supernova (2), although as I’ve only been able to find mention of that article at one site on the net, I am not sure as to how accurate or not it may itself be.

Interesting and much more supportive of a bolide than the previous misinterpretation of mold spores as carbon spherules. But, still no real PGE anomaly… or any other physical differentiation of the Younger Dryas from the other late Pleistocene glacial stadials related to the Dansgaard-Oesschger cycle.

If these scoria can’t be explained with terrestrial causes, they might be evidence of some type of bolide.

What, no models? Must have been one big explosion to eliminate so much CO2 that it caused an ice age! Seriously though, I’m happy to see some real digging and speculating on what is found. The whole thing appears quite plausible to me and I’ll be happy to read more (but I must add, I’m just an accountant, not a scientist). But the minute “global warming” is mentioned, I’ll turn on the authors in a heartbeat.

Leardog, the point of the article is that heat from cosmic impacts melted terrestrial material.
The source of the material is terra firma. The source of the heat was cosmic.
The signatures for volcanic or human heating are also different from what is seen in these samples.

Could it be that the “cosmic” items some how “parted the atmosphere” and opened the surface of the Earth directly to the vacuum of space. This is the only way the temperature could fall ~200F instantaneously [Sun pointing away or cooking (bbq mammoth) would have occurred]. A volcano or Earth shift could not do this!

Finally, an explanation for how the Mammoths froze. Climate “science” is settled except for those pesky cosmic events….

So as I understand it there were cosmic bodies impacting Earth resulting in melt-glass forming at temperatures of 1,700 to 2,200C. The hottest lavas are only 1,200C. No wonder there was a thick layer of charcoal – it must have set vast areas on fire. Does anyone know if melt-glass was formed as a result of the Tunguska event?

That it is found in California, Pennsylvania, South Carolina, Arizona, Syria, Germany and Venezuela suggests a widespead event and a large number of impacts. There must be some evidence of the original source.

Most of the blast-effected materials they’ve found so far are the kind of tektites, and particulates one might expect to see as distal ejecta falling out of atmospheric suspension as dust. The extreme temps required for the formation of the kind impact glass they’ve found exceed what can happen in volcanic processes; as well as any anthropogenic cause. Only an impact event can produce those temps.

If the thickness of the impact layer is a function of the proximity to the epicenter of one of the cluster airburst impact zones, keep in mind that the impact layer found in Lake Cuitzeo, in Central Mexico is a full 10 cm thick. It should also be noted that the stuff in Lake Cuitzeo is consistent with what you’d expect to see if a hypervelocity object large passed directly overhead, and was already well down into the atmosphere.

So one of the primary impact zones must be in Mexico, and within a couple of hundred miles of Lake Cuitzeo. The problem for researchers there is the amount of volcanic activity, and materials at that distance from the lake. And since no uniformitarian geologist of the past could’ve imagined such violence coming from the sky, there is a very good chance that most, if not all, of the melt formations, and planetary scarring of the Mexican impact zone are misdefined on geologic maps as volcanogenic.

DirkH says:
June 13, 2012 at 6:57 am
An asteroid that hits Syria and Pennsylvania at the same time? Hello?
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Remember the series of impacts of comets into Jupiter about a decade ago? They were widely spaced around a much bigger planet.

@DirkH Not a discreet “asteroid,” Dirk, but a swarm of bodies from a disintegrating comet. The fact that many big bodies are well known to slowly disintegrate into a wide pack(s) of smaller bodies, which can return each year, is widely ignored in the impact community. There is one coming around later this year: http://www.spacetelescope.org/images/heic0605a/ And Bill Napier has given us model to produce impacts of this kind for a sustained period(s) across much of the earth. Anyone reading this one paper for the first time, will increase their understanding of earth and human history many times overs: http://www.scribd.com/george1202/d/27825834-Napier-Astro-Model-Ras

FYA the researchers at the Younger Dryas Boundary layer quit thinking about single bolide, solid body, impacts a long time ago. The evidence is pointing to airbursts of large clusters of smaller fragments such as Linear 1, or Schwassmann Wachmann 3. And as W.M. Napier pointed out in ‘Paleolithic extinctions and the Taurid complex’ the breakup of comets is now a well recognized path to their destruction.

We saw SL-9 breakup into a “string of pearls” before returning to impact Jupiter. And most folks tend to refer to SL-9 as a model for a typical breakup mechanism. But in fact, to breakup a comet and stretch it out into a long string of fragments that way requires the concentrated tidal forces of a close passage to a very powerful gravity well; an unlikely scenario in the inner solar system.

The mechanism that caused the breakup of Comets Linear, and SW-3, was something different. Each produced large clusters of smaller fragments, not a string. And the mechanism that did so did not require the gravitational influence of any planet. It appears that the ices holding them together sublimated in the warmth of the sun, and they simply ‘came unglued’ like the wings of Icarus.

The impact evidence that’s been accumulating from the YD boundary layer is pointing to the Earth having collided with the debris from multiple large clusters of smaller fragments, such as those two objects; soon after the complete breakup of a good sized comet. And a very compelling case can be made that the parent body was the progenitor of the Taurid complex.

Add in some more anamolies….Mammoths were dining on temperate dandilions at the same latitude as the presumed, three mile thick Canadian ice sheet. One speculated scenario is that a possible impact occured over this ice sheet, hiding the impact crater. There is also a NA layer of nano-diamonds in this sediment layer. NASA recorded a meteor break up with multiple impacts on Jupiter, so this is a proven phenomena. The mammoths showed bone fractures consistent with direct vertical impact loads and the undigested food matter suggests near instant flash freezing. A massive, largely CO2 meteorite would be solid ‘dry ice’ in the 2.7K outer space, burst in the atmosphere and could have rained chunks of still frozen dry ice on our departed wooly mammal friends. Our web classroom has allowed us to find and share Truth beyond our greatest dreams. If left unmolested, humanity will ‘web’ our way out of all of our ignorant nightmares.

I’m probably wrong that the might be from this event, but if you use Google Earth and look over the multitudinous glacial lakes in southern Minnesota and northern Iowa, you will see quite a few that are round, with central peaks. (and one very large feature on the Wisconsin side of the Minnesota border that looks very much like an eroded, filled, and re-eroded crater)

mitchel44,
If one of the primary impact zones was the Laurentide Ice Sheet in the Great Lakes region as some suspect, then a natural consequence of the sudden melting of so much ice would be just such a meltwater pulse into the North Atlantic, and Arctic Ocean. And if a large percentage of the ice was flashed to steam, I wonder how long it would take it to presipitate back out of the atmosphere as rain. But I’m thinkin’ 40 days, and 40 nights, of torrential rains sounds sounds about right.

Faux Science Slayer says:June 13, 2012 at 9:03 am
I like your idea of a chunk of dry ice causing the instantaneous freezing. Actually any frozen gas would do that. It seems like a good solution to the extreme temperature change.

The history of “catastrophism” and “uniformitarianism” in science cannot be separated from religion. Very briefly, creation by a god implies one should see results that could be called catastrophic. Ancient Earth or “deep time” provides an alternative of slow and steady developments, such as sedimentation. With the religious overtones removed it became acceptable to consider significant rapid events – catastrophes.

Consider this as an example:
“Geologist J Harlen Bretz first recognized evidence of the catastrophic floods, which he called the Spokane Floods, in the 1920s.
. . .
Bretz’s view, which was seen as arguing for a catastrophic explanation of the geology, ran against the prevailing view of uniformitarianism, and Bretz’s views were initially held in disregard.”http://en.wikipedia.org/wiki/Missoula_Floods

John Marshall says:
Very interesting. I agree with Vince, above, in that the natural climate cycle was interrupted. It is certainly cold here in the UK and June already. The UK Met. Office blame the jet stream.
—
John, as scientists involved in climate change research keep pointing out to lay persons (and global warming doubters), climate is not weather. Coldness in a particular area does not indicate a change as great as global cooling, nor does warmer weather over the world or particular areas indicate global warming. Change over very long periods, such as centuries, not decades, indicate long-term trends:

“Empirical measurements of the Earth’s heat content show the planet is still accumulating heat and global warming is still happening. Surface temperatures can show short-term cooling when heat is exchanged between the atmosphere and the ocean, which has a much greater heat capacity than the air.” http://www.skepticalscience.com/global-cooling.htm

——–
Vince Causey said:
“Which means that the Younger Dryas was not part of a “natural rythm”, that the natural rythm induced ice age ended 20,000 years ago and not 12,000 years ago. Implications: we are now due for the next ice age.”

Mr. Causey’s statement is an example of the kind of thinking – supposition of causation from scant and/or irrelevant evidence – that helps spread myths about climate change, because it is not science-based. Those who don’t trust or understand how science works, however, may take up such notions and spread them, because they fit into their “commonsense” notions of global warming/climate change. Notions like this are common among global warming doubters, and spread in the conservative “echo chamber” (of which the WUWT blog is one example) rapidly …which is partly why it is so named.

Is there a need for perhaps considered “common sense” in climate science? Many posts here and elsewhere, as well as opinions frequently found in various media outlets, test climate science against the author’s “common sense” – and find the climate science wanting. This tantamount to Ludditeism: destroying the machinery of modern science.

There is an all-knowing Grand Climate Priest – Joe (??) the meteorologist and clearly uber-qualified climate science commentator, who appears periodically on Fox News ;-)). (Sorry, the man’s name escapes me – I don’t watch Fox.) He has used “common sense” and his meteorological knowledge to refute the best science accumulated by years of research by 98% of climate scientists.

There may be some “common sense” that applies to climate science – but it only applies in the context of the evidence and the science. However, in general, climate science is so complex that it requires years of study to obtain a degree in a related field, and years of research to determine trends and causation, correlated with the vast body of existing research. Moreover, the science would not be possible without advanced computers. There is little “common sense” involved in programming such computers, as they require advance technical and scientific knowledge far beyond “common sense.”

It’s true that no science is “settled,” since any evidence truly refuting a scientific axiom, theory, finding or other concept is always possible. However, none yet has refuted the vast and accelerating body of knowledge, agreed on in the main by 98% of climate scientists, that demonstrates this fact: Human activities have caused most of the global warming in the last 150 or so years.

I wish WUWT would become a science-based website that refutes myths promoted by the anti-science global doubting community. Haven’t seen much progress yet. Still seeing cherry-picked science and pseudo-science and discredited science quoted as comprehensive, real, peer-reviewed science. Looking forward to seeing that disappear someday.

“The truth is out there.” And scientists are finding it. Not using opinion, common sense, myth-spreading, poor logic or shouting. They use science. Live with it. Scientists are trying to help you live better lives – so please stop obstructing it.

So who the blazes were Younger and Dryas, or what happened to the Older Dryas, or where on earth is Younger Dryas, or where was Younger Dryas published, or what did Younger and Dryas think about Lewis and Clark, and were Younger and Dryas present at Rorke’s Drift ?

DirkH says:
June 13, 2012 at 6:57 am
An asteroid that hits Syria and Pennsylvania at the same time? Hello?
***************************
Remember the series of impacts of comets into Jupiter about a decade ago? They were widely spaced around a much bigger planet.
********************************************************************************************************************
I’m by no means religious, but the Book of Enoch talks about seven blazing stars which fell to Earth, and myths from all over the world refer to bright new stars which fell as seven flaming mountains, of how the oceans rose up in vast waves and totally engulfed the land, and how summer was driven away with a cold darkness that lasted several years. The Aborigines even had a name for them: the Water Girls. In the Atlantis story by Plato, Solon mentions that Atlantis sunk 9,000 years before.

I’m not saying the Atlantis myth is true, but myths do have a grain of truth to them. And they’re all so similar the world over. Maybe this is what they’re remembering? And event like that would definitely be remembered.

Stephen.
Thanks for the comments; this is what I like about WUWT, I learn a lot of things that I did not know. I did not know about the incredibly low temperatures need to freeze a mammoth, but it does make sense.. Likewise, I always thought that mammoths were “woolly” to protect them from the cold, Thanks again!

How often do such impacts occur? Although, past patterns do not mean future patterns will be the same (consider the weather). However, as large impacts have happened before they can happen again. We should be looking for the next one.

“John, as scientists involved in climate change research keep pointing out to lay persons (and global warming doubters), climate is not weather. ”

“Mr. Causey’s statement is an example of the kind of thinking – supposition of causation from scant and/or irrelevant evidence – that helps spread myths about climate change, because it is not science-based.”

You take light-hearted banter that 98% of posters here recognise as exactly that, and make sweeping generalisations about those such as myself who are “helping to spread myths about climate change.”

You then write: “I wish WUWT would become a science-based website that refutes myths promoted by the anti-science global doubting community. Haven’t seen much progress yet.”

Folks here at WUWT are by and large, a fairly amicable bunch, and a lot goes on in the way of general chit-chat and good natured humour on the subject of the thread. Of course, there are those who come in here and criticize this and that, make demands on what people should or shouldn’t say, and go out of their way to look for reasons to belittle others.

So, my friend, since you seek to impugn my name, please enlighten us here, and tell the good folks at WUWT what “climate change myths” – apart from my joke about the new ice age – I am guilty of spreading. i don’t what to hear any more of the substance-free arm waving you’ve already made, but actual quotes of what I have said and why they are myths.

I read Napier paper on the Taurid Complex recommended by swamp merchant. What I found most refreshing was the author clearly limiting the claim being made:
“The object of this paper is not to claim that such an encounter took place at 12,900 BP – that is a matter for Earthscientists – but to show that a convincing astronomical scenario can be constructed which seems to give a satisfactory match to the major geophysical features of the YoungerDryas Boundary data.”
Its a good read.

What is most interesting to me about this article is that it gives evidence that the impact was in fact multiple impacts. So just how many were involved? So far there is evidence for at least three (North America, Germany, and Syria), but there may possibly have been a dozen or more of various severity.

Probably not a bad idea to look for any tsunami evidence in the Atlantic.

Shoemaker–Levy 9 had 21 major fragments. So it’s perfectly possible to get multiple planetary impacts from a single comet.

Be careful using this as an authority. I have been severely scolded for simply wondering about some of the things this paper brings up.

One thing I’ve wondered is if the same comet of dry ice (or other frozen gas) could both cause extreme heat and extreme cold. The heat would be caused by friction as it entered the atmosphere, and by clobbering the earth. However could a pulverized mass of post-impact dry ice produce a dust-storm of super-cold powder, capable of flash freezing?

Another thing this paper mentions is wet muck and dry laoss across the north that contains particles which are not worn and smoothes, as they would be by wind, but rather have a microscopic jaggedness indicative of quick creation and deposition. Also they are not stratified, as they would be if laid down over time, but represent large amounts of stuff all laid down at once. Any geologist care to comment?

Lastly, the paper notes large deposits of bones from big animals, located in high places, with the bones showing stress fractures from above, as if the beasts had struggled upwards against the forses of some unimaginable flood of raining crud, muck and so forth. Small animal bones are not noted, so apparently the little critters didn’t even make it up the hills?

I can’t answer for everybody here, but I can certainly tell you that climate science modelling appears to violate norms of computer science practice in most fields. Models can be constructed any way you like, the best you know how, but they are not done yet. Then they have to pass tests, lots of tests. If they are still in development, they have to pass the tests over and over. The tests and their results have to be graded and kept. I can’t really imagine a modeller or IT professional from any field that could skip testing and still expect anybody to believe him. Clever people are all too prone to skip that discipline, and their work often suffers for it. So what we keep asking here is “Where are the tests?” How do you know that these models are correct, not just clever or well-informed? Otherwise they are not much more than sophisticated pictures somebody drew, using a computer. Sorry, but that’s my professional opinion, from a whole lot more years and experience than most of these guys have spent.

The main evidence for the YDB was the alleged micro-diamonds that proved to be nothing of the kind.
Bjorn Kurten has well explained the frozen mammoths.
Should we really try to displace AGW catastrophist myths with cosmic ones?

One element of meteorite/bolide intrusion that has not yet been reckoned
with is the plasma envelope that accompanies any object streaming through
our atmosphere at 18,000+ miles per hour.

NASA and DoD have gone to great lengths to minimize the problems this
envelope produces around re-entry vehicles (shuttles, etc.). Despite
“hardened” electronic systems, controlled flight orientation, and specific
structural design details they still end up with communications blackouts
and possible burn-though because of it.

Bolides tend to tumble as they descend, and the uncontrolled plasma
envelope melts the edges of the object. However, things coming in from
space tend to have very low space-cold interiors. The shaking and bouncing
during uncontrolled descent tend to loosen parts of the amalgamation, and
temperature/pressure variations lend themselves to the object coming
apart before it hits terra firma.

However, they aren’t any real studies of what happens as
this plasma-encased thing passes over and explodes. Nuclear air burst tests
were all single-point-in-time single-point-in-atmosphere events using
specifically shaped munitions. A bolide breaking up and parts exploding
while other parts continue down the track might be compared to a MIRV
attack without fixed targets. However, there aren’t any real
studies of what happens as this non-weaponized plasma-encased thing
passes over in an arc and explodes. A bolide of any good size on the move
with a plasma envelope doesn’t allow a 100% comparison with any
nuclear explosion.

If there is data or studies of what happens when plasma-encased objects
actually hit the ground, nobody’s sharing it. There’s even less
information on what happens when such an object, with it’s plasma
envelope intact, penetrates the surface of the earth.

Are they grants out there to investigate this ? Will I need
a security clearance ?

“The main evidence for the YDB was the alleged micro-diamonds that proved to be nothing of the kind.”

This is untrue. Your confirmation bias is showing. In fact nano-diamonds in the Younger Dryas boundary layer have been confirmed many times over since 2007. And the groups who published work that failed to replicate the stratigraphic work of Firestone 2007 have been largely discredited by rebuttals in refereed literature. Perhaps you should read the recent PNAS paper titled Evidence from central Mexico supporting the Younger Dryas extraterrestrial impact hypothesis, specifically the section titled “potential misidentification of markers” before you make such absolute statements.

For those interested in actual earth impacts the there are several papers written by Dennis Orphal and the late David J Roddy. Very interesting reading.
In the late 70’s the connection with ring structures and meteorites was confirmed. After the connection was made, and researchers learned what to look for; satellite images were reviewed leading to the discovery of many ring structures in northern Europe and elsewhere.

The Okotoks Erratic train – a debris field resulting from a catastrophic release of meltwater from near Jasper, Alberta, that ended up in the Pacific in Washington – resulted from a sudden burst or sustained, higher-than-normal meltrate of the alpine and continental glaciers at 12,500 YBP. If the impact at 12,900 YBP caused a sudden but short cooling, the “melt-load” would have been high when warming returned.

Something triggered a melting that was beyond the established capacity of a series of ice-dammed lakes along the eastern edge of the Rocky Mts. The short-lived cooling period – a relative cooling period – could have caused the prior, stabilized melt and release processes to stall. It was then the return of more “seasonal” conditions that created a non-sustainable though non-castastrophic melt to occur. The inability of one ice-dam to hold its lake then triggered a consecutive collapse of the other lakes downstream.

The main thing I like about more evidence being found is that it means a lot of “scientists” are going to have to eat a lot of very snotty words.

Criticism of the hypothesis that the Younger Dryas was caused by a cosmic encounter has not been polite or academic. Much of it was from the same CAGW folks that were hung up on the idea that the thermohaline circulation was responsible. Tomwys’ Law strikes again!

Before jumping on the comet bandwagon, a number of dots need to be connected and some critical questions need to be addressed. For example, how could a single event, even with multiple projectiles, cause an ice age that lasted for more than 1,000 years? Surely not from atmospheric dust and if not that, then what? The Younger Dryas is not the only climatic event during the post glacial maximum period—there are also a number of others spanning the time from 14,500 radiocarbon years (about 17,500 calendar years) to 10,000 14C years (about 11,500 calendar years). These are well known, well dated, and well documented in ice cores and in the global glacial record. So the question is, how could an impact event cause both multiple warming and cooling events over a 3,000 year period? Doesn’t seem logical at all for either impact or volcanic events.
Some other questions pertain to the evidence for the proposed cosmic event. Geologists are used to studying micro-images of rocks and looking at the two samples shown in the paper, it is obvious that both show definite flow structures that closely resemble glass flows from volcanic lava. The statement “Morphological and geochemical evidence of the melt-glass confirms that the material is not cosmic, volcanic, or of human-made origin. “The very high temperature melt-glass appears identical to that produced in known cosmic impact events such as Meteor Crater in Arizona, and the Australasian tektite field,” is very vague. What morphological and geochemical evidence? As for these specimens being identical to trinitite from atomic blasts, there is surely no flow structure in the photos shown so how can they be identical?
The bottom line here is—a lot more dots need to be connected and these critical questions (as well as a number of others) need to be addressed before concluding that the Younger Dryas was caused by a cosmic impact.

Faux Science Slayer says:
June 13, 2012 at 9:03 am
——————
I also like the ‘dry ice (frozen co2) raining down on unsuspecting beasts’ theory.
I’m not sure how frozen co2 causes forest fires, though I could ask Dr. Mann at what temperature would wood start burning and could an ice cycle cause a forest fire?

So one of the primary impact zones must be in Mexico, and within a couple of hundred miles of Lake Cuitzeo. The problem for researchers there is the amount of volcanic activity, and materials at that distance from the lake. And since no uniformitarian geologist of the past could’ve imagined such violence coming from the sky, there is a very good chance that most, if not all, of the melt formations, and planetary scarring of the Mexican impact zone are misdefined on geologic maps as volcanogenic.

Dennis, you make a good point. Lake Cuitzeo is immediately north of the Trans-Mexico Volcanic Zone (I’ve been there), so volcanism did have to be taken into account for that study. There may, indeed, be misidentification of features in that area.

The features you often talk about are a considerable distance from both Lake Cuitzeo and the volcanic zone, so you do make a good argument that volcanism as an explanation is misidentification there.

I’ve always thought the YD event over-rated. Here a few others overlapped (from GISP2 with shifted x axis to overlap the similar events). Note the similarities in duration and amplitude of the min max (entering and exiting the events) between the three events (they tend to ride on top of the obliquity signal, single 1200yr cycles by themselves, but doubled up when obliquity coincides like the three examples overlapped).

If the YD was caused by meteors, then they must have a period of roughly 1200 yrs or so (throughout the GISP2 record, both during glacial and interglacial (though much attenuated during the interglacial as sensitivity is obviously much lower with warmer temps, hence the bimodality),

I’m sticking with the man wiped them out theory (along with all of the giant Moa relatives piled up on the islands heading towards hawaii, whenever man shows up), and that the cooling of the YD is the same as the exiting of all of the preceding 1200yr (and doubled up) events. Same rise and fall,,,

Curiously, the oldest known human-made religious structure, Göbekli Tepe, was built around 12,000 years ago, about 20 miles from the Syrian border.

I’ve made the same connection. There is no ‘curiously’ about it. You make a very pertinent observation/connection. It is too early in the game for this to be a solid connection, but in the end I am certain you will be proven correct.

It IS cool that Göbleki Tepi is so close to the Syrian site, isn’t it? That it dates about 900 years later puts it within the YD, and that would seem to make sense. If the global climate was cooler by several degrees that area – and all of the Fertile Crescent – would have had a much better climate for agriculture. Such a place would have been ideal for humans to start making a comeback.

Yeah Steve, The large ablative airburst event that produced the LIbyan Desert Glass without making a crater hit a big desert full of clean silicate sand. It’s impossible to mistake the resulting blast-effected materials (beautiful clear glass) as being volcanic.

But what form do we expect ablative melt to take if the same kind of large ablative airburst hit a target surface that was was an active volcanic zone? And how would we diferentiate between volcanogenic materials, and the blast-effected materials of an airburst, when the parent materials were volcanic to begin with?

@Mark June 13, 2012 at 1:52 pm:
“Shoemaker–Levy 9 had 21 major fragments. So it’s perfectly possible to get multiple planetary impacts from a single comet.”

It is amazing how inimical, how much in denial, the geological and astronomical people are about cometary events on Earth and even more so multiple events, given the lesson of SL/9. If comets can hit Jupiter, they can obviously hit the Earth. If multiple comet fragments can hit Jupiter, then multiple comet fragments can hit the Earth. Especially given that we go through the Taurids twice a year, and the Taurid progenitor also spawned Comet Encke (3.3 year orbit), which is far bigger than any fragment of SL/9. The Taurids are far from being mapped, so we do not know what is out there playing hide-and-seek every time we go through the Taurids.

The number of hostile scientists about this is utterly incomprehensible. And the head of NASA – Dave Morrison – is the leading denier. NASA puts essentially no money at all into coming up with a workable plan to protect the Earth from such events, whether singular or multiple. If one is found to be bearing down on us, our goose is cooked and another Göblecki Tepi is in our future about 900-1,000 years. I don’t want to sound like an alarmist – here of all blogs – but one impact the size of the larger half dozen of the SL/9 fragments will send us back to both the stone age and the ice age, making global warming a moot point.

@Edward – You make good points. You seem to be talking in part about the Heinrich Events, the rafting of rock debris into the N Atlantic by slowly melting icebergs, which are thought to have calved off glaciers in northern Canada. I would say that a lot of what is said about the Heinrich events is interpretations, not necessarily fact. In the Pleistocene similar events were called Dansgaard-Oeschger events. The climatic as a cause of the debris fields is only the current thinking on it. Roll back the clock 50-75-100-150 years ago and there were many seemingly valid interpretations in science which we know now were wrong. Like its connected paradigm – the oceanic conveyor and Lake Agassiz fresh water incursions – this is all IMHO a house of cards. Ask famed climatologist Carl Wunsch about these and he will tell you they are fantasy.

So, what is the actual truth of it? We are in the middle of it, so we can’t see the forest for the trees yet. All the cards are not yet on the table. The totality of the evidence is not in yet (as this study shows). We are at some point along the continuum of evidence discovery and analysis. Conclusions on either side are premature. And as this study shows, reports of the demise of the YD impact event are greatly exaggerated. I am enjoying the progression of events NOW. Watching this unfold is very entertaining. And enlightening.

Another thing this paper mentions is wet muck and dry laoss across the north that contains particles which are not worn and smoothes, as they would be by wind, but rather have a microscopic jaggedness indicative of quick creation and deposition. Also they are not stratified, as they would be if laid down over time, but represent large amounts of stuff all laid down at once. Any geologist care to comment?

Caleb, you might be interested to know that overlaying many of the Carolina bays is a layer of quartz sand that has exactly the qualities you speak of here. The grains are remarkably uniform in size and have sharp edges, as if “laid down at once.” In addition the sand is not stratified. In fact, it even drapes over the rims of the bays, a blanket that extends from inside the bays to the outside of them. Though often close to water, the sand does not seem to be from local sources. The sand is so consistent and pure it is used to make a high quality of glass, with almost no pre-processing.

How to explain? Not by fluvian action. Not by aeolian action. Not by slow deposition. Impact? Perhaps, but not proven, not by a long shot.

The Book of Enoch equated stars with angels and planets with archangels.

How do you get agriculture from a catastrophe?

Mammoths survived on Wrangel island till 4kya, at 71N latitude. That was probably when humans arrived.

Instantly frozen mammoth carcasses is a creationist myth.

Frozen decayed carcasses have been dated to various ages. I’m not aware of any dating to 12900BP. –AGF
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
I for one would rather consider the opinions of a well thought out treatise on possible events that caused the catastrophic demise of the Wooly Mammoth and other temperate region grazing animals and their predators such as :-http://www.grahamkendall.net/Unsorted_files-2/A312-Frozen_Mammoths.txt
rather than off the cuff prejudiced arm waving. Caleb, for the Graham Kendal link, and Swampmerchant for http://www.scribd.com/george1202/d/27825834-Napier-Astro-Model-Ras have obviously put a great deal of thought into their replies, and both links point in the same direction.
As to how you get agriculture from catastrophe, ask yourself, you have been a hunter all your life, all the available live game is destroyed, how would you survive but by grains, vegetation and perhaps roots and legumes ?
As for Wrangel Island, that is another argument and not in itself enough to refute the main evidence, dating being notoriously unreliable particularly when high radiation is involved.

It seems that extraterrestrial bodies are much more negatively impacting on our climate and life on earth than an increase of a few parts per million CO2 molecules in the atmosphere. To defend ourselves and the planet from the latter threat we are spending trillions of dollars/euros with the exuse of saving the planet (from a non-existing enemy), while about the former threat which seems to be more real and far more devastating, we are doing abolutely nothing. Honestly though, I do not believe that we can do anything to save ourselves from any one of thesentwo threats, one because it is not real and the other because it is so devastatingly unstoppable.

Whose to say all of the ice ages were not caused by such events? We keep looking for a regular pattern on a world is more susceptible to the cosmos then anyone wants to admit. Random just drives people insane doesnt it? Honestly, knowing what we do know should drive us to expand our existence off the vulnerable place we call Earth, before the cosmic pinball game throws us another whopper.

Jesting aside, though, a most interesting post and set of comments. My problem with the YD is its square-wave shape. Yes, I can accept the possibility of an impact cause, but what about the recovery? A single pulse might well cause the observed sudden drop in temperatures, but temperatures would then be expected to recover asymptotically back to the trend line. That’s not what we see. Many thanks to Edward for his overlay of similar events. That looks as if there is some sort of natural time constant working with such events, since they’re all of about the same duration and amplitude. It does rather look as if a multiple impact 12,900 years ago might well have been coincidence, especially in light of the recent posting here which showed no long-term cooling from volcanic events.
We watch with interest.

Before jumping on the comet bandwagon, a number of dots need to be connected and some critical questions need to be addressed. For example, how could a single event, even with multiple projectiles, cause an ice age that lasted for more than 1,000 years?
****

That’s the 64m$ question. I agree impact effects themselves wouldn’t last more than a few decades — prb’ly less.

I think it boils down to the “tendency” for the earth to fall into glacial conditions — the conditions that occur 90% of the time in the last 2 mil yrs. Milankovitch cycles are the trigger, but something else causes the rapid temp declines that occur not only when interglacials end, but even during the glacial periods as D/O events. IMO, it has to be some kind of major ocean/atmospheric reorganization to a colder pattern. If an impact causes a temporary severe cooling, then that reorganization might be initiated. Ice-cores show a slow decline from N hemisphere solar max to near min (Milankovitch) is enough to abruptly end just about every interglacial in the last 1 mil yrs. So a brief but severe impact cooling (especially localized in N hemisphere where glacial conditions originate) ought to be able to do it.

As for the comically naive suggestion that a catastrophe led to the invention of agriculture, let’s ponder the question of how agriculture did get started. Certainly not by hunters only; by hunter-gatherers, possibly. By grain gatherers, almost certainly. Here’s how.

Grain gatherers bring their baskets of grain to the hut or tent. The baby tips the basket over and they do their best to clean it up. After the next rain sprouts grow and they harvest grain right by the tent or hut. Most likely a tent, because there was no reason for a stationary hut before they knew how to grow their own grain. So they visit a previous camp site and lo, there is grain growing right where the baby spilled the basket. And after this happens a few thousand times some wise guy says, why should only the baby spill the grain? So eventually they start building permanent huts.

Now if you can tell us how sudden or gradual climate change helped the baby spill the basket, be our guest. People did not start eating grain because of a meteor shower. Maybe a meteor knocked the basket over. –AGF

>Dr. Lurtz says:
>June 13, 2012 at 6:57 am
>Could it be that the “cosmic” items some how “parted the atmosphere” and opened the surface >of the Earth directly to the vacuum of space. This is the only way the temperature could fall >~200F instantaneously [Sun pointing away or cooking (bbq mammoth) would have occurred]. A >volcano or Earth shift could not do this!

I have been thinking this must be what happened. I am glad to see someone else say it.

WUWT should be required reading for 9 -12 graders. With luck home Schoolers do just that.

I certainly looks like it was a swarm of meteors. I would not be surprised if the Earth got hit more than once by the swarm until she cleaned the area. The Younger Dryas stadial, was a 1300 ± 70 years. So repeated hits over time make a kind of sense.

“As for Wrangel Island, that is another argument and not in itself enough to refute the main evidence, dating being notoriously unreliable particularly when high radiation is involved.”
======================================================================
And what if no radiation is involved? This handwaving allows you to take every frozen mammoth no matter what its C14 date and claim it died together with every other frozen mammoth found. It’s bad enough saying humans didn’t wipe out the big game, when the archeological evidence is overwhelming that everywhere humans first appeared the big game disappeared. Climate change is the rule, and the critters usually cope. CNGC (catastrophic natural global cooling) is no more scientific than CAGW, so your blaming dead mammoths on a meteor is doubly unscientific, triple so when you reject C14 dating of mammoth carcasses.

The whole Mammoth meme getting pretty tired, and old. In point of fact, if folks would take the time to actually read the papers produced by researchers working on the stratigraphy of the Younger Dryas Boundary layer, instead of getting caught up in the tripe propduced by crappy science reporting, they’d know that not even one paper has ever said that Mammoth existed below the Younger Dryas Boundary Layer, but not above it.

…
The number of hostile scientists about this is utterly incomprehensible. And the head of NASA – Dave Morrison – is the leading denier. NASA puts essentially no money at all into coming up with a workable plan to protect the Earth from such events, whether singular or multiple. If one is found to be bearing down on us, our goose is cooked and another Göblecki Tepi is in our future about 900-1,000 years. I don’t want to sound like an alarmist – here of all blogs – but one impact the size of the larger half dozen of the SL/9 fragments will send us back to both the stone age and the ice age, making global warming a moot point.

Steve Garcia

You mean like this short notice discovery??
Only 3 days notice of its existence, larger bodies might be noticed earlier, but even so just a few days or weeks prior notice is hardly sufficient to do anything at all to mitigate an impact let alone prevent one.

The near-Earth asteroid 2012 LZ1, which astronomers think is about 1,650 feet (500 meters) wide, will come within 14 lunar distances of Earth Thursday evening.
…
2012 LZ1 just popped onto astronomers’ radar this week. It was discovered on the night of June 10-11 by Rob McNaught and his colleagues, who were peering through the Uppsala Schmidt telescope at Siding Spring Observatory in Australia.

@pkatt June 14, 2012 at 12:09 am:
“Whose to say all of the ice ages were not caused by such events?”

That is pretty much my take on Heinrich Events and Dansgaard-Oeschger Events, that they come about because we pass through the denser part of the Taurids and get whacked. If the Taurids are essentially regular it only seems logical that our damaging periods would happen with some regularity. In fact, if one starts from that assumption and works backward, one might be able to make some falsifiable predictions about the makeup of the Taurid stream.

All this doesn’t make it true, but surely something that should be looked into.

What is most interesting to me about this article is that it gives evidence that the impact was in fact multiple impacts. So just how many were involved? So far there is evidence for at least three (North America, Germany, and Syria), but there may possibly have been a dozen or more of various severity.

Probably not a bad idea to look for any tsunami evidence in the Atlantic.

Nyeshet – Exactly correct. The original YD impact group has been maligned because they didn’t have the entire multi-disciplinary picture right on the first go-around. But this is an event that needs ongoing disvcoveries – and ones that can be looked at from that perspective. If that first Firestone group had not put the ida out there a lot of this evidence would be being identified/interpreted as something else altogether. At some point someone had to step up and say, “Look, if we put 2+2 together here, we see the answer being 4.” Evidence like this paper is going to keep on coming up, now that people have a framework within which to place the evidence. The evidence does not have to be enigmatic or anomalous anymore.

Shoemaker–Levy 9 had 21 major fragments. So it’s perfectly possible to get multiple planetary impacts from a single comet.

This is still very early in the game. Now that people are beginning to be open-minded about this possibility they are able to put multiple minds together in several fields, so people are now LOOKING to see if these impact sites exist, using the best thinking they can put into it. Expect more and more of this kind of find. The science will prove out in the end, one way or the other. As time has moved along, truly independent researchers are finding such evidence. Some are still sitting on the fence on interpreting their finds, but their evidence is still consistent with this hypothesis.

All your points are exactly correct. Although Mark Boslough is doing hypervelocity modeling (at Sandia National Labs, I think), we don’t know how many variations he has performed.

The desnsity/friability of the object is of prime importance, as well as how long it is in the atmosphere. A vertical descent is in the atmosphere the shortest amount of time. Yet almost every meteor I’ve seen on video is shown on some low trajectory, which means a relatively long time in the atmosphere – and subsequently more chance of exploding above ground. And the low point of any tangential or near-tangential trajectory varies, with air density varying along with that, meaning wildly varying heat build-up. All these variables make for a very complex scenario, and if comet advocates haven’t figured it all out yet, no duh! It takes time to develop the right questions to ask so that the right experiments can be run and the right ground evidence be collected and put into perspective.

There is a bit of discussion at CosmicTusk.com on this, very much along the lines you are discussing. But CosmicTusk people have very little (if any) effect on what runs to do. We DO need some idea of what is happening when these kinds of events occur. There are all kinds of solid ideas out there, but no way of sorting through them yet.

We are all very early in the continuum of this inquiry. As in any overturning hypothesis, at the beginning the naysayers have had the bulk of evidence on their side. But that is because the pros collection of evidence has had few artifacts yet. We keep on seeing the adding of new evidence, and the great bulk of what is being found is supportive of the premise. The weight of the evidence is turning…

“The main evidence for the YDB was the alleged micro-diamonds that proved to be nothing of the kind.”

This is untrue. Your confirmation bias is showing. In fact nano-diamonds in the Younger Dryas boundary layer have been confirmed many times over since 2007. And the groups who published work that failed to replicate the stratigraphic work of Firestone 2007 have been largely discredited by rebuttals in refereed literature. Perhaps you should read the recent PNAS paper titled Evidence from central Mexico supporting the Younger Dryas extraterrestrial impact hypothesis, specifically the section titled “potential misidentification of markers” before you make such absolute statements.

Laurence Crossen says:
June 13, 2012 at 3:50 pm
Sorry, I just read one article I thought had settled it.

Touché, Dennis.

You saved me the trouble of saying the same thing: Those Daulton, etc., claims are well rebutted and show that Daulton’s own team failed to do due diligence. Unfortunately, his unsupportable snack got 50 times the press of the rebuttals.

To whit: Thank you, Anthony, for posting this! This post is probably expanding the exposure of this important study beyond all other news sources put together.

Before jumping on the comet bandwagon, a number of dots need to be connected and some critical questions need to be addressed.

Don, your questions are all valid and do need to be addressed. I would say give it time. It is early in the game, and more and more evidence is turning up. Expect to see answers to your questions, one by one, as this all fleshes out.

Some other questions pertain to the evidence for the proposed cosmic event. Geologists are used to studying micro-images of rocks and looking at the two samples shown in the paper, it is obvious that both show definite flow structures that closely resemble glass flows from volcanic lava.

The statement “Morphological and geochemical evidence of the melt-glass confirms that the material is not cosmic, volcanic, or of human-made origin. “The very high temperature melt-glass appears identical to that produced in known cosmic impact events such as Meteor Crater in Arizona, and the Australasian tektite field,” is very vague. What morphological and geochemical evidence? As for these specimens being identical to trinitite from atomic blasts, there is surely no flow structure in the photos shown so how can they be identical?

All that is available now is the Abstract, so why don’t we wait till we can see the paper?

The bottom line here is—a lot more dots need to be connected and these critical questions (as well as a number of others) need to be addressed before concluding that the Younger Dryas was caused by a cosmic impact.

Fair enough. Yes, let’s be skeptical, as long as an open mind comes with the doubt. That is the way of science: Let the chips fall where they may. Momentum is moving in the direction of eventual confirmation. But it may be a long slog.

Tim Mantyla @ June 13 12:10 pm launches into a supercilious rant of a type common to CAGW true-believers: anyone who disagrees with his preferred conclusions is “anti-science,” regardless of how much scientific evidence is cited in support. Notably, TM fails to explain precisely what he thinks is “unscientific” and offers no countervailing argument.

TM apparently was set off by the observation by Vince Causey that the evidence for a possible extraterrestrial impact origin for the YD implies that “the Younger Dryas was not part of a ‘natural rhythm’, that the natural rhythm induced ice age ended 20,000 years ago and not 12,000 years ago. Implications: we are now due for the next ice age.”

I would quote TM’s scientific basis for objecting to Causey’s observation, but there is nothing to quote. TM’s rant is unconnected with any rational argument. What follows is mere diatribe.

To me, Causey raises a scientifically valid and interesting point. Since TM seems not to have understood, let me set the matter forth in more detail:

1. For the last 1-2 million years the earth has experienced recurrent glaciations on a periodicity of roughly 100,000 years. The evidence is presented and reproduced in so many places that I won’t bother with a citation; it doesn’t seem to be controversial even among CAGWists.

2. The recurrent glaciation events are not Swiss timepieces, but they are surprisingly uniform in period for geological occurrences, consistent with proposed astronomical explanations. The most parsimonious expectation is that the periodicity of glaciation will continue into the future. Thus if we can properly establish the onset of a glaciation event (such as the beginning of a warm period) then we may extrapolate to the onset of future events in the cycle.

3. Interglacial warm periods tend to last about 15,000 years. The onset of warm periods is abrupt, whereas the decline is gradual; thus the duration of a warm period depends on how you define the amount of decline needed to mark its end. But by 15,000 years after onset of a warm period, the cooling trend is evident (on a millennial time scale) for all preceding glaciation events of the last 1,000,000+ years. Notably, the peak warming of the present interglacial (the “Holocene optimum”)
occurred 6,000-8,000 years ago, and the recent warming remains well below the temperatures of 6,000 years ago. The earth appears to remain in a secular cooling trend.

4. If the Holocene onset should be dated to the end of the Younger Dryas 11,900 years ago, then we might reasonably expect a few more millennia of warmth. If however the Holocene onset should be dated to the warming period before the Younger Dryas cooling, then the current interglacial period is several thousand years older. Based on prior glaciations, we should anticipate a new glaciation might begin much sooner.

So, TM, exactly what is “unscientific” in the preceding argument? Do you disagree with any of the above factual assertions? If so, please explain; as I mentioned already, I don’t think the timing and duration of previous glaciations are very controversial for either warmists or skeptics. Do you think the logical inferences are unsupported? If so please explain precisely how.

TM, you have castigated the science here without offering specifics. It’s time for you to engage with the actual argument rather than retreat into generalities: put up or shut up.

Some of you newcomers to skeptical climate science should take a look at this graph:
Insolation at 65 degrees north latitude in June varies by 100W/m^2 TOA and by similar amounts wherever the edge of the northern ice happens to be. Oxygen isotopes and reconstructed temperature follow Milankovitch Cycles closely, with a lag long enough to account for melting and freezing ice caps. That’s 100W/m (TOA) versus 1.6W for CO2 IR. CO2, volcanos, and meteors are hardly blips on the screen. –AGF

when the archeological evidence is overwhelming that everywhere humans first appeared the big game disappeared

But the big game animals have not disappeared in Africa and parts of Asia, where mega-fauna remain despite the presence of humans beating the bush for the cook-pot for a very long time on those continents.

But the big game animals have not disappeared in Africa and parts of Asia, where mega-fauna remain despite the presence of humans beating the bush for the cook-pot for a very long time on those continents.

Evidence here, as with various other special-interest issues that Anthony tends to fight shy of, of an emotional poiarization of views between those who dismiss “naive believers” but are then shown to be naive believers themselves who are in denial of various bits of hard evidence that will not go away – and those who sound suspiciously naive / transcendental-ranting at first, and have dubious and even objectionable website links, but then show interesting hard evidence.

To me, this shows one can be well-versed, intelligent and open in one area and completely naive and intolerant in another area. To me, the challenge is how to find blog language and behaviour that allows courteous exploration of subjects where at least some of the associated material is, or seems to be, objectionable. Right now I’m working closely with someone who is a brilliant and innovative scientist and engineer in one direction, but is (at present!) firmly convinced in AGW.

It is important to be able to investigate things without people making the mere investigation impossible. This requires that investigators take extra trouble to show their approach is in keeping with the spirit of science, if not its familiar letter; and that those who criticize don’t forget that the best scientists show mystical, intuitive sides that at first sight don’t look scientific (Newton for example) – and that many have been ruthlessly punished for such things, in all ages, in ways that are all too familiar – and that ultimately the Universe is a mystery and a wonder of great intrinsic beauty (a word that cannot exist in a purely materialist view of reality).

Something I’ve noticed in this thread is what amounts to a lot of off topic straw man arguments; the mammoth extinction meme, and the myth that they were all flash frozen at the same time being just one of them.

The simple fact is that the authors of the Younger Dryas Impact Hypothesis have never stated that the event caused the extinction of the Mammoths. What they have shown is the global emplacement of an assemblage of markers in the YD boundary layer that can only be explained by a major impact event of catastrophic proportions, and that there is only one other global layer in the stratigraphic record with the same assemblage of impact markers as the YDB; the KT boundary layer that marks the extinction of the dinosaurs 65 million years ago. The specific claim of the authors of the YD impact hypothesis is that only a major impact event that’s different from anything that’s ever been studied before could have produced those markers globally. Multiple large cluster airburst events are proposed.

And the discovery of more impact markers that date to 12,900 YA is the only claim that is being made in the new paper that’s the topic of this thread.

Nor have the Authors of the YDIH ever categorically stated that the event was the trigger for the start of the Younger Dryas cooling. They have simply pointed out that the timing of the emplacement of a global impact layer with only one other comparable example in the stratigraphic record, that being the KT boundary, coincides with the start of the Younger Dryas Cooling and the Megafaunal extinctions 12,900 YA.

But humans never appeared suddenly in Africa–as early man developed into a dangerous hunter the animals had time to gain a healthy respect for them.. Eurasian mammoths are a somewhat more difficult question, but they specialized in sub-Arctic forage, where humans were also late arrivers. In the Old World the devlopment of mesolithic technology was more sudden than human arrival. –AGF

Albeit off topic (and mentioned above), as far as exiting the current interglacial period (as much as I’d like it to start soon to prevent current political and monetary strategies), since the orbital parameters are very similar to that which occurred 420kyrs ago (eccentricity and obliquity in phase), our current interglacial could last another 2kyrs. Here is a graph of overlayed starts of interglacials (Vostok). The similar 420kyr interglacial was ~2kyrs longer than the current interglacial.

In all likelihood, not one thing, but a combination of problems for the mega-mammals probably led to their demise.

And to Gail, Earth may have just been in the crossfire between Jupiter and the Sun when this comet was torn apart by their gravitational pulling or whatever. Jupiter and the sun probably did most of the cleaning out. The stream of material coming off the comet could not have just stopped in outer space with nothing to slow it. I just hope all of the big material was captured by gravity and gobbled up by the two giants in our solar system.

As for the comically naive suggestion that a catastrophe led to the invention of agriculture, let’s ponder the question of how agriculture did get started. Certainly not by hunters only; by hunter-gatherers, possibly. By grain gatherers, almost certainly. Here’s how. ~~~~~~
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
By transposing the particular to the general you created the comedy. You asked how a catastrophe COULD lead to agriculture, I gave as logical an answer as your proposition which may well be true, but not exclusive.
For photos and some idea of the extent of the catastrophic die off, Alaska, Canada, through northern Europe and Siberia ~ 10,000- 12000 yrs ago see :-http://www.s8int.com/boneyard4.html
and read all the pages for other catastrophic evidence in fossil beds

For photos and some idea of the extent of the catastrophic die off, Alaska, Canada, through northern Europe and Siberia ~ 10,000- 12000 yrs ago see :-http://www.s8int.com/boneyard4.html
and read all the pages for other catastrophic evidence in fossil beds
****

Thanks for the link, Julian. Astonishing. That should convince anyone that the evidence of a non-human-caused catastrophe killing massive numbers of mega-fauna is overwhelming.

As for the comically naive suggestion that a catastrophe led to the invention of agriculture, let’s ponder the question of how agriculture did get started. Certainly not by hunters only; by hunter-gatherers, possibly. By grain gatherers, almost certainly. Here’s how.

Now if you can tell us how sudden or gradual climate change helped the baby spill the basket, be our guest. People did not start eating grain because of a meteor shower. Maybe a meteor knocked the basket over. –AGF
**********************************************************************************************
The question of the start of agriculture (Off topic I know, sorry) was mentioned in Ryan & Pitman’s “Noah’s Flood”, about the re-flooding of the Black Sea and Stephen Oppenheimer’s “Eden in the East”, in which he posits the rise in sea levels over the South China Sea causing human migration bringing agriculture from there to Mesopotamia. Ryan & Pitman in particular offer the “Oasis hypothesis” according to which the Ice Age aridity of central Asia trapped bands of humans and prey animals close to water and so humans had to take up husbandry to avoid starvation. Not sure if either cause is rapid enough to count as a catastrophe, though.

beng says:
June 15, 2012 at 5:37 am
****
Julian Braggins says:
June 15, 2012 at 3:02 am
=================================================================
That link is some of the silliest nonsense we’ll ever hope to read. You could not support a word of it with good evidence. –AGF

M Wilson says:
June 13, 2012 at 7:01 am
…
That it is found in California, Pennsylvania, South Carolina, Arizona, Syria, Germany and Venezuela suggests a widesp[r]ead event and a large number of impacts. There must be some evidence of the original source.

Buried (silted over) at the bottom of Hudson Bay, for the biggest chunk, with accompanying smaller meteors airbursting elsewhere?

Naively speaking, James Bay has always looked like an entrance (exit?) ‘ramp’. And Hudson Bay is so damn circular …
:)

That it is found in California, Pennsylvania, South Carolina, Arizona, Syria, Germany and Venezuela suggests a widesp[r]ead event and a large number of impacts. There must be some evidence of the original source.

Larry Ledwick (hotrod ) says:
June 14, 2012 at 12:50 pm
…
You mean like this short notice discovery??
Only 3 days notice of its existence, larger bodies might be noticed earlier, but even so just a few days or weeks prior notice is hardly sufficient to do anything at all to mitigate an impact let alone prevent one.

The near-Earth asteroid 2012 LZ1, which astronomers think is about 1,650 feet (500 meters) wide, will come within 14 lunar distances of Earth Thursday evening.
…
2012 LZ1 just popped onto astronomers’ radar this week. It was discovered on the night of June 10-11 by Rob McNaught and his colleagues, who were peering through the Uppsala Schmidt telescope at Siding Spring Observatory in Australia.

There’s doubt about the size. With objects like this, the assumption is made that the albedo is very low (about like asphalt), and size is estimated by brightness. But some bodies, like Vesta, have high albedo. So this is either largish dark, or small bright. Nobuddy nose.

Guys, even if we had a year’s notice, we don’t have a plan, not a workable one. The money put into a planetary defense system isn’t a hill of beans. We can put something up to nuke an incomer, but we are as likely to create a shotgun effect as anything else. Which is worse, one big whack or a thousand little ones? A garrote or a bullet though the brain?

We are the first generation in history to have the ability to stop us going back to the stone age, and Dave Morrison, head of NASA, plays ostrich on our behalf. Napier and others started talking about this back in the 1980s, and we’ve done nothing but go backward on it ever since. Outside of better computers, our hardware is really about what it was at the beginning of the Space Shuttle program.

So it doesn’t matter if it is dark or bright. If it is as big as the bigger half of the SL/9 fragments our goose would be cooked.

Fear of CAGW is a whole lot more rational than fear of imminent meteoric catastrophe. It’s on a par with space invaders. Sagan and his ilk on the one hand spent tens of millions on the Arecibo Antenna hoping to pick up signs of intelligent life, and now even nuttier kooks say quit sending signals or you’ll let the evil aliens know where we are. Crackpots all. You stand a better chance of ET communication by praying.

Life on earth is clearly home grown–no evidence of ET interference. Maybe evolution has been steered now and then by catastrophes but they are very rare. Distribution of species is clearly controlled primarily by continental drift and climate change due to such slow drift. And secondarily by global climate change, where ice ages have been the exception. If any political pretender ran on a campaign of salvation from meteors I would vote for whatever crackpot was running against him.

I’ll tell you what a few of mankind’s biggest problems are.
1) Medical advances assure the survival of the least fit. It is of course our duty to be humane and help the weak but the consequences are clear: we enable the perpetuation and multiplication of “defective” genes. Treatable genetic diseases will inevitably become more prevalent unless we resort to genetic engineering or eugenic bigotry. I offer no solution.
2) Narcotic prohibition is destroying one Latin American country after another. We persecute those who escape from a drug trafficing hell of our making. The solution is obvious: repeal prohibition.
3) While Marxist ideology is suffering except in those countries that have been ruined by drug traffic, totalitarian regimes continue to hold sway in much of the world, and to prevent humane military intervention.
4) Ideological climate pseudoscience continues to subvert the scientific method on a par with Creationism.
5) Driving continues to be dangerous until airbags are designed to prevent inury due to collisions with meteors. –AGF

“Humane military intervention” – an oxymoron if ever there was one. Preventing it is a good thing. (I almost missed your snarc.)

Most (if not all) of the Latin totalitarian regimes have been put in place by the U.S. at the behest of U.S. economic interests such as the infamous U.S. Fruit Company. Our govt continues intervening ‘humanely’ to a lesser degree than in earlier times, thanks in no small part to GW Bush’s inability to handle walking and chewing gum at the same time, for which the Venezuelans, Ecuadorians and Bolivians, in particular, thank him for not assassinating their populist movement leaders. Argentina, Chile, and Brazil, especially, have thrived by this later weakening of U.S. hegemony efforts – much of it done by Milton Friedman and his ‘Chicago Boys’ through the other interventionist tool, the IMF. The nations most closely aligned to the U.S. govt remain among the most totalitarian. So the solution seems to not only be to de-prohibit narcotics but to stop intervening “humanely” in the affairs of other countries in our hemisphere.

On 1.) : At least one study around 2000 suggested that Roe v Wade in 1972 cut down inner city unmarried motherhood and that it had a subsequent effect in lowering the crime rate in 1990s, just when those unborns were coming of age. That suggestion set off a furor and (as far as I’ve been able to tell) no one has had the temerity to replicate it. Whether other studies falsified it, I don’t know; I haven’t seen anything – and I am sure I’d have perked up my ears, since it seemed to make sense to me.

BTW, I favored Roe v Wade as a young man, because I grew up in a neighborhood where children were left to their own upbringing, and I saw many parents who never should have been parents. From what I saw many of us turned out to be real drags on society, especially including my own two brothers. This, of course, implies that I myself should have not been born to my less than functional parents. Like you, I have no solution, but I wanted to add perspective. (And, as I said, this it OT, and I have no intention of hijacking one of my favorite topics.)

While it seems contradictory on WUWT, I do think we need to raise an alarm about comets and other NEOs so that an adequate plan for planetary defense can be funded properly. In doing so I do not advocate that the effort be used to shoehorn a world government. Something on the lines of a joint scientific effort limited to this effort would suffice quite well. This limitation can be safeguarded well enough. And once a methodology is proven and in place only a small cadre would be needed to ‘man the ramparts’.

That link is some of the silliest nonsense we’ll ever hope to read. You could not support a word of it with good evidence. –AGF
****

I read some more, and yeah there is alot of nonsense on that site. But the stuff about massive die-offs of mammoths & other mega-fauna ~12900 yrs ago are just recounts of observational evidence, so I don’t think the other kookiness is relevant. There are other sites w/no kookiness that recount the same observations.

The web copy of this document was an apparent OCR scan of the original, link below. I edited this extract from:

Journal of the transactions of the Victoria Institute, or Philosophical Society of Great Britain
pp. 40-43

THE IVORY ISLANDS IN THE ARCTIC OCEAN.
By the Rev. D. Gath Whitley.
[…]
The enormous quantities of mammoths’ bones and tusks found by Liakoff in these islands raised the curiosity of the Government, and the Russian officials at Yakutsk ordered a surveyor named Chwoinoff to proceed to the islands, and to survey them thoroughly. Chwoinoff left Yakutsk for this purpose in the early part of 1775, and reached Liakoff’s station on the mainland at Ustyansk in the end of March. He crossed the bay to Svaiatoi Noss, and reached the first island discovered by Liakoff, and which has always afterwards been called Liakoff’s Island. He found that this island — which contained the huts of the diggers for fossil ivory — was of considerable size, but with the exception of some high mountains, it seemed to be wholly composed of ice and sand. Such was the enormous quantity of mammoths’ remains, that it seemed to Chwoinoff that the island was actually composed of the bones and tusks of elephants, cemented together by icy sand. The horns of buffaloes (or rather of musk-oxen) and rhinoceroses were also wonderfully abundant. The sandy shores and slopes were full of mammoths’ tusks, and when the ice cementing the cliffs was thawed by the heat of the sun, the sand fell down in great quantities, bringing with it great numbers of elephants’ tusks, of which these cliffs seemed to be full.
[…]
On the death of Liakoff, the Russian Government granted the monopoly of trading in these islands, in 1805, to a mercliant of Yakutsk named Sirovatskoi, who sent his agent Sannikoff to explore the islands, and, if possible, to discover more islands in these wonderful regions. Discoveries now commenced which were as remarkable as those of Liakoff, and which amply repaid Sirovatskoi for his labour and outlay. In 1805, Sannikoff discovered to the east of Kotelnoi, a large island which he called Fadeyeffskoi ; and in 1806, the yommer (sic) Sirovatskoi discovered another large island still further to the east, which received the name of New Siberia.* Two smaller islands — Stolbovoi and Belkowa — were at the same time discovered. These islands were full of mammoth bones, and the quantity of tusks and teeth of elephants and rhinoceroses, found in the newly discovered island of New Siberia, were perfectly amazing, and supassed anything which had as yet been discovered.
Before long — as was natural — disputes arose as to the monopoly of collecting the fossil ivory in these wonderful islands, and petitions were addressed to the Russian Government on the subject. This induced Count Romanzoff, then Chancellor of Russia, to order Hedenstrom, a Siberian exile, to explore the islands, and Romanzoff fitted out the expedition at his own expense. Hedenstrom started from Ustyansk, near the mouth of the Yana, on March 19th, 1809, taking with him two companions, and for three consecutive seasons they examined the islands. Hedenstrom found that the quantity of fossil ivory on the first island found by Liakoff (i.e., Liakoff’s Island) was so enormous, that, although the ivory diggers had been engaged in collecting ivory from it for forty years, the supply seemed to be quite undiminished. On an expanse of sand little more than half a mile in extent Hedenstrom saw ten tusks of mammoths sticking up, and as the ivory hunters had left these tusks because there were other places where the remains of mammoths were still more abundant, the enormous quantity of elephants’ tusks and bones in the island may be imagined.
Sannikoff — who accompanied Hedenstron — was equally amazed at the quantity of the remains of the mammoth in Liakoffs Island, and — like Chwoinoff thirty years before — he declared that the whole soil of the island seemed to be formed of elephants’ bones.

Thankyou for that fascinating link. Context works wonders, and it is clear that Rev. Whitley is a scholar to be reckoned with. More questions are raised than I have the ability to address, but one particularly intriguing observation I must repeat:

“The surface of the island consisted
of a bed of thick moss on which many beautiful flowers were
growing, but underneath were cliffs of pure ice. It was possible
to strip off the moss like a carpet from a floor, and beneath was
pure ice which never thawed.”

With this Whitley provides a solution to the problem, one touched on by
Pfizenmeyer as quoted by Sue Bishop at the link I provided above (http://www.talkorigins.org/faqs/mammoths.html).
The mammoths’ food grew on top of the ice, so that the animals were doomed to a life of dangerous grazing, and whether they died of old age or a fall through the ice, their remains were bound to preserved for millennia.

Still we cannot help but wonder if the accounts are not somewhat exaggerated. For one thing, why is it no longer possible to find such hords of tusks as are claimed to have existed if these accounts are not embellished. For another, how would such an abundance of ivory have affected the market, when we must suppose that a high price of mammoth ivory would have been due to the difficulty of transport rather than short supply. Is it possible to distinguish between elephant and mammoth ivory? Of which were Victorian keyboards and trinkets composed?

At any rate, even if there is some truth to these tales they fall short of providing evidence for either Noah’s flood or for meteoric catastrophe: the carcasses accumulated in the ice over long periods of time. The more numerous their remains the more difficult it becomes to argue that they all died at the same time–such populations could not have been supported on the surface at any given time.
–AGF

“But in fact, to breakup a comet and stretch it out into a long string of fragments that way requires the concentrated tidal forces of a close passage to a very powerful gravity well; an unlikely scenario in the inner solar system.”

Is it possible that a near miss (near hit) with possible atmospheric penetration might result in a capture of the disruption fragments? Perhaps one site is an initial glancing contact point and the others are due to returning fragments.That type of event might lead to a large cloud of ballistic extra-atmospheric debris that could have taken a long time to decay.

One theory for the origin of the moon postulates it as the result of a glancing impact with a Mars-sized body.

“Is it possible that a near miss (near hit) with possible atmospheric penetration might result in a capture of the disruption fragments? Perhaps one site is an initial glancing contact point and the others are due to returning fragments.That type of event might lead to a large cloud of ballistic extra-atmospheric debris that could have taken a long time to decay”

Good question. Based on what I’ve been able to learn so far, I’d say yes. But when you’re considering the potential effects of multiple clusters of fragments of varying size, from dust grains up to stuff that must have been hundreds of meters across, as the Earth passed through Taurid progenitor’s debris field, then the correct answer is probably, “all of the above”.

The thing is, in spite of numerous examples of fragmented comets in short period orbits that cross the orbits of all the planets of the inner solar system like comets Scwassmann Wachmann –3, or Linear-1, none of the impact simulations to date have ever considered the impact effects of a cluster of fragments of an icy body soon after it’s complete breakup. NASA planetary sciences are still stuck on the gradualist model of one lone bolide at a time ballistic/kinetic impacts.

With the exception of some work on the Libyan Desert Glass, and the Tunguska event of 1908, by Mark Boslough at Sandia Labs. (see Large Aerial Bursts and the Impact Threat) all the simulations we see are based on the 60+ year old point-source approximations that came out of the nuclear test detonations of the cold war years. None of them accounts for preservation of the downward momentum of a hypervelocity object that detonates in an airburst like Tunguska did, or the event that produced the Libyan Desert Glass without leaving any shock-metamorphic effects such as a crater. In other words, those old point source detonations without preservation of momentum are not valid for estimating the destructive force of a hypervelocity airburst. Much less the destructive potential for a large cluster of them. Or what the resulting planetary scarring of something like 10,000 Tunguska class airbursts over a period of just a few minutes might look like.

They’re pretty heavily invested in that single bolide model. And they’ve been working from the assumption of a steady, and consistent impact flux for decades. They work from that unproven assumption when they use the number of craters in a given surface on the Moon or Mars, to estimate the age of that surface. But all it would take is the impact of one large cluster of small fragments such as we see in the two images above sometime in the past to cause them to over estimate the age of the resulting planetary surface by billions of years.

And to even acknowledge the possibility of a cluster impact event means throwing decades of work counting craters to estimate the ages of planetary surfaces in the inner solar system right out the window.

Blackville, South Carolina. This dated site is in the rim of a Carolina Bay, one of a group of >50;000 elliptical and often overlapping depressions with raised rims scattered across the Atlantic Coastal Plain from New Jersey to Alabama (SI Appendix, Fig. S4). For this study, samples were cored by hand auger at the thickest part of the bay rim, raised 2 m above the surrounding terrain. The sediment sequence is represented by eolian and alluvial sediments composed of variable loamy to silty red clays down to an apparent unconformity at 190 cm below surface (cmbs). Below this there is massive, variegated red clay, interpreted as a paleosol predating bay rim formation (Miocene marine clay >1 million years old) (SI Appendix, Fig. S4). A peak in both SLOs and spherules occurs in a 15 cm—thick interval beginning at 190 cmbs above the clay section, extending up to 175 cmbs (SI Appendix, Table S3).

This is revealing. The clay under the rim of this CB is evidently right at the YD boundary (the onset of the YD). This is both completely in disagreement with the 50-100kya datings of the CBs we’ve seen AND in completely in agreement with the CB equals YDB idea. I don’t want to take this and run with it, but just note it for future reference.

One thing about this is that the previous datings of the CBs, as I understand them – have been taken on the rims, too. How does one have some of them dated to 12.9kya and some at 50-100kya? Multiple events seems to be the only explanation, but then the alignments are miraculous.

Evidently there is more to come on this…

I’ve been skeptical about the previous datings taken from the CB rims, which run in the 50,000 to 100,000 range usually (but not always). Not because I want the CBs to happen at the YDB, but because I don’t think the rims are the proper points of measurement for this. It does make sense to do it there if the only possibility for their formation is sedimentary or aeolian (wind-blown), which I vociferously disagree with. But it assumes something is true, even though 70 years of trying have failed to convince the rest of science. If the CBs were easily pawned off as formed by the wind, then they would not be the mysterious enigmas they are today. They are mysterious because scientists for the last 70 years have seen through that hypothesis; it just doesn’t work.

If ET impact is considered a possibility, then the rim is conceivably a tortured, discombobulated mixing zone, making it the LEAST likely place to give a proper dating. It’s like taking DNA samples from the surface of a body – there might be all sorts of other DNA in there. For the Cbs there may be a mixture of millions of years old materials with materials that DO date to an impact. Ergo, some other location for dating needs to be determined, one that is fair to both hypotheses.

Thank you much for the article in the Journal of the transactions of the Victoria Institute, or Philosophical Society of Great Britain. I had no idea that was available online. I’ve had my eye out for it for years.

Fred Hoyle – always ready to risk his neck outside his specialism (and annoy the hell out of those whose toes he trod on) was very much anti-Croll/Milankovich on the grounds of C/M’s feeble forcing. The current commitment to C/M depends massively on positive feedbacks, i.e. high climate sensitivity. (Could this be WHY it’s so popular…) Hoyle thought that glaciations required cosmic causes for both initiation and termination, and reckoned some kind of impact. Of course he spelled out a very specific complete theory (“Ice” – 1981) which was much criticised (for reasons which were no doubt valid, at least in part). Nevertheless, the main general point he made was that we should be preparing for the next glaciation. Adapt or die. (I think he suggested a geo-engineering approach, the deliberate storing of heat in the deep ocean by major pumping work – possibly loony, possibly dangerous, I wouldn’t know.)